Orthopedic procedures for the replacement of all, or a portion of, a patient's joint have been developed over the last thirty years. In unicompartmental knee replacement (also called “partial” knee replacement) only a portion of the knee is resurfaced. This procedure is an alternative to total knee replacement for patients whose disease is limited to just one area of the knee. Because a partial knee replacement is done through a smaller incision, patients usually spend less time in the hospital and return to normal activities sooner than total knee replacement patients.
Currently, the procedures used to prepare the bone and seat the implants are generally referred to as open procedures. For the purposes of this discussion, the term “open procedure” will refer to a procedure wherein an incision is made through the skin and underlying tissue to fully expose a large portion of the particular joint surface. In both total and unicompartmental knee arthroplasty, the typical incision for an open procedure is about 8-10 inches long. After the initial incision in the skin, the internal wound may be enlarged to fully expose the areas to be prepared. While this approach provides surgeons with an excellent view of the bone surface, the underlying damage to the soft tissue, including the muscles can lengthen a patient's rehabilitation time after surgery. While the implants may be well fixed at the time of surgery, it may be several weeks or perhaps months before the tissues violated during surgery are fully healed.
With the above in mind the surgeon strives to perform surgery using minimally invasive procedures to reduce both the incision size and the damage to soft tissue, thereby shortening a patient's rehabilitation time. Partial knee replacement procedures generally involve the consecutive steps of making an incision and exposing the joint, resecting the distal end of the femur, resecting the proximal end of the tibia, sizing the femur and establishing external rotation, finishing the femur, sizing and finishing the tibia, performing trial reductions, and implanting the prosthesis components. Although effective, it is known that the joint space within which the surgeon must work is restricted and the cutting and removal of bone can be a challenging task when working in this small joint space.
Accordingly, there is a need for a method and an instrument that can be used to create additional space at the surgical site and facilitate the steps in the preparation of the knee joint to receive the components of a knee prosthesis. As described in detail below, the presently disclosed invention eliminates many of the known problems by combining cut operations and also providing fixed reference points for mounting of the cutting guides.